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1. Shreya Deodhar et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 2( Version 1), February 2014, pp.384-387
RESEARCH ARTICLE
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OPEN ACCESS
Effective Use of Colors in HMI Design
Shreya Deodhar, Prachi Agrawal, Aditi Helekar
(Electronics & Telecommunication engineering in University of Pune , India)
(Electronics & Telecommunication engineering in University of Pune, India)
(Electronics & Telecommunication engineering in University of Pune, India)
ABSTRACT
Nowadays majority portion of the operations in modern manufacturing industries are performed by the
implementation of automation technology. All automation technologies employ a graphical Human Machine
Interface (HMIs) to interact with the machine. Color is a major component of the HMI. The main characteristic
of the HMI is that it should be intuitive and user friendly. With the use of appropriate colors, the HMI can be
designed in such a way that the user focuses only on the specific part of the interface at that specific time
period. Choosing the right color for the background, control buttons, alarms, text and other objects is very
critical to design a good HMI. This paper will briefly examine theoretical and practical aspects of these
components and the established techniques for the effective use of color in graphical HMI. A survey was
conducted in order to support the findings of the study.
Keywords - Colors, Display, Graphics, HMI-Human Machine Interface, Objects
I. INTRODUCTION
In order to achieve high productivity from
the automated machineries used in the industries, the
issues of end-product equipment safety, ease of
operation and reducing human error become
extremely important. Human machine interfaces
(HMIs) provide means to the operators to see, touch
and control high stress industrial processes through
touch screen displays. The two major factors to be
considered while designing the HMI are, the screen
must be able to hold operator’s attention with
maximum display clarity and the design must allow a
person with no training or little experience to be able
to successfully operate a machine.
According to a previous study, every color
creates a different emotion in a human being [2].
According to Murch, a well-known human factors
researcher, “Color can be a powerful tool to improve
the usefulness of an information display in a wide
variety of areas if it is used properly”[1]. The
communicative properties of a color can help in
designing an effective HMI. For example, Blue
triggers the sense of calm and red color of danger [3].
For a good design, the HMI would rather be simple
than having big flashing animated lights, vessels with
bright colors, or moving conveyors. Putting big
bright measurement units is a bad idea. Also number
of colors included in the design should be limited.
II. THE PROPOSED TECHNIQUES
2.1 Background Color
It has been observed during many previous
studies that warm colors such as red, yellow, and
orange are better in drawing one’s attention to
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particular areas of the display [3]. Use of such warm
colors should not be used for large areas of the screen
as they degrade the performance by continuously
drawing attention to them. Use of blue and green
colors may fail to draw attention. Thus it can be
argued that cool colors make better backgrounds and
theme colors because of their tendency towards
balanced representation of feelings [3].
An HMI graphic should always have a dull
background (preferably grey). There should be no
animation and crossing lines should be avoided, so
that the operator does not get distracted from
important data. Primary colors (red, green, blue)
should never be used as background. Black and white
colors are generally not used in background due to
their characteristic of causing a glare. According to a
study [3] brown and grey colors are dull and do not
draw attention. It is always recommended to use
pastel shades such as light grey, light brown in the
background. These colors are easier to look and
provide good contrast for the dark/ brighter colors
(i.e. red, yellow etc) used for other components in the
display page. While incorporating multiple pages,
multiple shadows are used for each page so that the
operator can visually identify different pages even
from a distance.
2.2 Display Colors for Objects
According to SCADA/HMI Design Standard
[4], there are few colors those specifically should be
used for representing certain operations. They are:
Red Stop, Emergency or Prohibition
Green Start or Safe Condition
Yellow  Warning
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2. Shreya Deodhar et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 2( Version 1), February 2014, pp.384-387
Blue Mandatory Operation
These colors should be clearly visible to the
operators. Also if these color conventions are being
followed in a design, then they should be strictly
followed and similar colors should not be used to
indicate any other actions. This will help reduce the
misinterpretation or confusion for the operator. Dark
colors should not be in screen in large blocks because
they can create complementary color image retention
on the retina [5].
Let us consider a standard object (Meter)
from the microchip’s graphic library. As shown in the
figure 1, it shows six colors. This object all by itself
will not indicate any information. Colors have to be
chosen according to the application. Figure 2
indicates a speedometer it is a simple meter
consisting of three colors. It can be observed that
though minimum amount of text is present on the
screen, it is not at all hard to interpret. The figure 3
uses the same object however now with different
colors. The purpose of this screen can also be easily
interpreted. It is the meter indicating the solder
mixture composition. The green indicates the
desirable area and the actions to be taken in case of
the red areas are clearly mentioned. Figure 2 and
Figure 3 are superior representations. When asked in
the survey, 99% of the users were able to correctly
identify the representation.
Attention to detail is important. It is typical
to use bar charts to show relative positions and
values. While this may be better than simply showing
numbers, it is inferior to the use of moving elements
since as the bar’s value gets low, the bar disappears
as seen in Figure 4.
The human eye is more likely to see the
presence of an object rather than the absence. As
shown in Figure 5 the representation can be
improved. Also as the quantities are one below the
other they can be easily compared.
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2.3 Text
Text in the HMI screen is the easiest way to
convey information to the operator. However a
screen should contain minimum text. Proper font and
color should be used in the display so that an operator
should not face any difficulty in reading and
understanding the information. It is always wise to
choose fonts which are commonly available in most
of the computers, such as Arial, Times New Roman
etc.
The size of the text should be as such that
the operator can read the key information from
several feet distance without and all the text should
be black. Alarm text should be red and warnings in
yellow. Thin blue lines (like blue text) tend to blur,
and small blue objects tend to disappear when we try
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3. Shreya Deodhar et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 2( Version 1), February 2014, pp.384-387
www.ijera.com
to focus on them. Colors such as blue, green, yellow
should be avoided for text. These findings were also
proved by the supporting survey.
2.4 Alarm
Alarm and event information are the most
important parts in the HMI screen design because it
enables the operator to identify system operations and
avoid critical situation those may arise during a
process.
An event occurs whenever an operator reacts
to alarms or makes any changes to the system.
Alarms consider changes in a process or in its control
system (i.e. operator action, configuration changes
etc) those need to be recorded. HMI touch-screen,
alarms and process feedbacks should consist of the
following types:
Informative or Predictive: No action
required. These can use green color, as these are not
urgent and are needed only for user feedback. e.g.
“Process Complete” (informative).
Warning: Process may or in 99% cases may not
produce damage even if no corrective action is taken
immediately. These
generally use
yellow.
e.g.”Improper Lubrication”.
Blocking: The controller takes an action
against any risky condition to protect the process and
further operation is prevented until the reason is
cleared. e.g. “Motor Jammed”
When a fault occurs, the separate alarm
indicator appears next to it . The indicator keeps on
flashing while the alarm is unacknowledged (one of
the very few proper uses of animation) and ceases
flashing after acknowledgement, but remains as long
as the alarm condition is in effect. People do not
detect color change well in peripheral vision, but
movement, such as flashing, is readily detected.
Alarms thus readily stand out on a graphic and are
detectable at a glance.
Bright colors are primarily used to bring or
draw attention to abnormal situations, not normal
ones. Screens depicting the operation running
normally should not be covered in brightly saturated
colors, such as red or green pumps, equipment,
valves, etc. When alarm colors are chosen, such as
bright red and yellow, they are used solely for the
depiction of an alarm-related condition and
functionality and for no other purpose. Figure 6
shows a fault depiction. In further details the fault
should be specified as shown in Figure 7. If color is
used inconsistently, then it ceases to have meaning.
[5].
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Proper screen layout is very important for a
good HMI display. Generally, a human operator scans
an HMI screen as any other regular screens, starting
from top left corner to right and then down the
screen. The human scanning pattern is as shown in
Figure 8. So, the important objects of a system
should be in an area within the page where the
operator’s attention goes easily. The alarms should be
on the top of the page. Any graphical image object
should be on the center left with key data on the
center right of the page.
It is recommended that start, stop or controls
are kept in the lower left side and the navigation on
the lower right side of the page.
2.5 Process diagram:
Many a times while designing the HMI, it is
important to include a representation of the complete
process flow in the HMI screen. This makes the
operators to visualize the plant and identify the
locations of the measurements. A good HMI should
always have consistent process flow direction and the
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4. Shreya Deodhar et al Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 2( Version 1), February 2014, pp.384-387
use of color must be limited. An HMI graphics
should always include trends so that the operator can
easily follow the behavior of a plant and monitor
possible excursions.
In doing this, vessel levels should not be
shown as large blobs of saturated color. A simple
strip depiction showing the proximity to alarm limits
is better [5]. The Figure 9 shows an appropriate
depiction of a process diagram.
[3]
[4]
[5]
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Tharangie K G D, Irfan C M A, Yamad K
and Marasinghe A.,” Kansei Color Concepts
to Improve Effective Color Selection in
Designing Human Computer Interfaces”,
IJCSI International Journal of Computer
Science Issues, Vol. 7, Issue 3, No 4, May
2010
SNS
HUMAN-MACHINE
(HMI)
STANDARDS
Bill Hollifield, ”A High Performance HMI:
Better
Graphics
for
Operations
Effectiveness”, Presented at the 2012 ISA
Water & Wastewater and Automatic
Controls Symposium Holiday Inn Castle
Resort, Orlando, Florida, USA – Aug 7-9,
2012
III. CONCLUSION
As HMI systems are turning to be the
principal point of contact between the user and the
machine, a good HMI display makes this interaction
flawless and smooth. This study concludes that
appropriate use of color proves to improve the design
of an HMI tenfold. In order to focus the user’s
attention, colors chosen for the background should be
dull and those for objects and text should be
attractive. Also it was concluded from the supporting
survey that, generally users are not able to
differentiate between the shades of green and blue.
Finally we can conclude that in an HMI the
representation should be crisp and to the point. No
unnecessary decoration should be tolerated .Use of
color should be made only to add information thus
making a better design.
IV. ACKNOWLEDGMENT
The authors would like to thank Prof. Mrs.
T.S. Khatavkar of Department of Electronics &
Telecommunication Engineering,
Pune Vidyarthi
Griha’s College of Engineering and Technology,
Pune for her valuable guidance.
REFERENCES
[1]
[2]
Taylor, J. M. and Murch. G. M. , “The
Effective Use of Color in Visual Displays:
Text and Graphics Applications”, Color
Research and Applications Vol. 11
Supplement (1986), pp.S3-10.
Murch, G. M.,” Physiological Principles for
the Effective Use of Color”, IEEE Computer
Graphics and Applications 4, (Nov.1984),
49-54.
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